CODEWITHSUNDEEP
bash
slaxor
slaxor

Reputation: 516

How do I break out of this loop in bash

I want to break out of this loop when grep doesn't match its pattern. The "higher" goals here were:

.

#!/bin/bash
set -ex
i=1
RERUN=0
while [ ${RERUN} == 0 ]
do
   ((i++))
   echo -n "Rerun${i}"| tee >(grep --color=always 'Rerun[123]' ; export RERUN=$?)
   echo ${RERUN}
   sleep 1
done

My guess why its not working is that is has to do with different shell levels

Upvotes: 0

Views: 310

Answers (2)

Charles Duffy
Charles Duffy

Reputation: 295272

I might write this like so:

#!/bin/bash

generate_output() {
  local i=0
  while :; do
    (( ++i ))
    printf 'Rerun%s\n' "$i"
    sleep 1
  done
}

while IFS= read -r line; do
  printf '%s\n' "$line"
  [[ $line = Rerun[123] ]] || break
done < <(generate_output)

Note that there's no need to communicate between the two processes with a shared variable -- sending a SIGPIPE to generate_output by closing the file descriptor it's writing to suffices.

Upvotes: 1

slaxor
slaxor

Reputation: 516

I found a solution:

#!/bin/bash
# set -x
i=0
RERUN_FILE=$(mktemp)
declare -a TESTDATA=("run" "run" "run" "last" "run" "run" "run" )
while ! $(grep -q 1 ${RERUN_FILE})
do
   echo -n ${TESTDATA[$i]}| tee >(grep --color=always 'run'; echo -n $? >${RERUN_FILE})
   ((i++))
   sleep 1
done
rm ${RERUN_FILE} # do your dishes after the meal

Upvotes: 0

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